Reduce the synthetic timeout delays for GestureProvider unit tests

This reduces the clock time needed to complete all GestureProviderTests from
~4 seconds to ~20 milliseconds.

Review URL: https://codereview.chromium.org/189563002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256113 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256113